Audience measurement of exposure to media content, such as television programming, is typically performed by generating and collecting viewing records and/or other exposure information from an audience made up of a group of statistically selected households. Some example audience measurement systems determine signatures representative of the media content presented (e.g., displayed) for consumption (e.g., viewing) by the audience member(s) in each of the statistically selected households. In such an example system, the determined signatures are included in the viewing (or, more generally, exposure) records collected for the group of statistically selected households
In general, signature-based media content identification techniques use one or more characteristics of the media (e.g., audio/video) content being presented to an audience member/household to generate a substantially unique proxy or signature (e.g., a series of digital values, a waveform, etc.) for that content. The signature information for the content being presented to the audience member/household may be compared to a set of reference signatures corresponding to a known set of reference media content sources. When a substantial match is found, the media content being presented to the audience member/household can be identified as corresponding to a known reference content source associated with a matching reference signature with a relatively high probability. Accordingly, the ability of a particular signature-based identification technique to measure audience exposure to media content depends, at least in part, on the ability to match reference signatures corresponding to as many different potential reference content sources as possible.